Raman scattering in hexagonal InN under high pressure

Abstract

The behavior of the ${E}_{2}$ and ${A}_{1}(\mathrm{LO})$ optical phonons of hexagonal indium nitride under hydrostatic pressure was studied using Raman spectroscopy. Linear pressure coefficients and the corresponding Gr\"uneisen parameters for both modes were determined for the wurtzite structure up to $11.6\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, close to the starting pressure of the hexagonal to rocksalt phase transition of InN. Raman spectra acquired within the $11.6\phantom{\rule{0.5em}{0ex}}\text{to}\phantom{\rule{0.5em}{0ex}}13.2\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ pressure range suggest that wurtzite InN undergoes a gradual phase transition, and the reverse transformation exhibits a strong hysteresis effect during the downstroke.